Frequency selective scattering properties of dielectric gratings

The extension of the optoacoustic scattering phenomenon to microwave and millimeter-wave applications has been investigated by many researchers using various approaches, including the coupled-wave, leaky-wave theories among the analytic methods and the unimoment, finite-difference formulations among the numerical techniques. The present study indicates that most of these methods are very time-consuming in terms of obtaining relevant data such as reflection and transmission coefficients at a single frequency. Therefore, a computationally efficient method of solution based on fundamentally sound principles needs to be chosen for the purpose of simulating the scattering process from a dielectric grating over a wide band of frequencies. Only Kong´s (1977) second-order coupled-wave approach has been found to suit this purpose well. As an example, the reflection and transmission coefficients of a dielectric grating with a thickness to modulation periodicity ratio of 1.713 were determined.<>